@Hedy1962 Had my RTKR done in July 2017. OS did not place a button on my patella as he said it was too fragile. Personally, I think he didn't have the proper sized button for my patella. Anyway, in the meantime, when standing from a low chair, I heard a little pop. Returned to OS in July 2018 to do a revision and add a button to the patella. Xray showed that I indeed broke off a little piece of my patella, however, it was never removed and has no affect on my knee function. Not sure if your situation is the same but just thought I'd share. Never a dull moment with these knees!!!!